Iran has continued uranium enrichment despite a directive from the Security Council to suspend such activities, the United Nations atomic watchdog has said in a new report.

The report also said that without greater transparency and spot checks, the International Atomic Energy Agency cannot affirm that Tehran's nuclear programme is solely for peaceful purposes to produce energy and not weapons.

"Iran has not agreed to any of the required transparency measures, which are essential for the clarification of certain aspects of the scope and nature of its nuclear programme," IAEA Director-General Mohamed El Baradei told the Security Council in the report, which was released on Wednesday.

As announced by Iran itself, the country has continued uranium enrichment, which can produce fuel for providing electricity or at a much higher level making nuclear bombs, it said.

Iran insists its programme is purely for energy production but the United States and its allies maintain it is for making weapons and in December, the Council imposed limited sanctions and called on Tehran to suspend all enrichment related and reprocessing activities.

El Baradei reported that Iran continued to feed uranium into enrichment machines at the Pilot Fuel Enrichment Plant.

Between November two and February 17, it declared enriching some 66 kilos of uranium hexafluoride (UF6) to levels below five per cent, consistent with fuel production, in two 164-cascade machines.

A much higher level of enrichment is required for bombs. The report stressed that Iran had for nearly 20 years concealed its nuclear activities in breach of its obligations under the Nuclear Non-Proliferation Treaty and it was this discovery in 2003 that gave rise to the current crisis over its nuclear programme.

Given this history, 'it is necessary for Iran to enable the Agency, through maximum cooperation and transparency, to fully reconstruct the history of Iran's nuclear programme," El Baradei stated.

"Without such cooperation and transparency, the Agency will not be able to provide assurances about the absence of undeclared nuclear material and activities in Iran or about the exclusively peaceful nature of that programme," added.

The Security Council called on Iran to promptly ratify the additional protocol to the NPT, which in effect guarantees the IAEA access on short notice to all declared and, if necessary, undeclared facilities in order to assure the absence of undeclared nuclear material and activities, but Tehran has not done so.

"The Agency is able to verify the (current) non-diversion of declared nuclear material in Iran," El Baradei says.

"The Agency remains unable, however, to make further progress in its efforts to verify fully the past development of Iran's nuclear programme and certain aspects relevant to its scope and nature.